1. Field of the Invention a
The present invention relates to apparatus and methods for reconditioning engine cylinder heads.
2. Prior Art
In the prior art, various apparatus has been advanced for reconditioning cylinder heads. U.S. Pat. No. 3,782,847 shows a method and apparatus utilizing a drill press like machine, and a cylinder head support frame that permits rotation of the head in two mutually perpendicular horizontal axis, and thus, entails a quite large support, and complex method to obtain proper alignment of the valve guide bores.
Other devices provide for proper positioning of guide members in the head itself, such as that shown in U.S. Pat. No. 3,764,204 issued to Kammeraad. This device has a valve guide boring fixture that mounts directly into the valve head and guides a boring tool. It utilizes a tapered alignment pin for obtaining the necessary alignment of the boring tool with the valve guide bore.
U.S. Pat. No. 3,799,687 also relates to tooling for valve guide reconditioning, and comprises a fixture that mounts onto the valve head and can be used for guiding a reamer or tool that can be either hand held or machine held.
U.S. Pat. No. 3,977,805 shows a tool bar holder for use in reconditioning automotive or engine heads, aligns a guide bar with a row of valve guides, and using alignment pins as well, which pass through a slot in this bar after insertion in selected valve guides. The device is clamped onto the cylinder head, and the head is not held in a precise arrangement with any particular tool during operation. Other devices that illustrate the state of the art include U.S. Pat. No. 3,534,639 which shows a pivoting head for a drill press that permits tilting the axis of a drill bit or reamer. Other patents which illustrate the state of the art include U.S. Pat. Nos. 3,034,380 and 3,333,487.
Also, prior art devices which used a bubble level for alignment have been known. However in this application an alignment bar which permits establishing a plane in a desired position is used and provides great accuracy in operation.